Retransmission of data to or from a mobile station, MS, or user equipment, UE, is previously known. If data is received in error, it is requested for retransmission. If errors are frequent, data is requested for retransmission frequently. When the relative amount of transmissions that are retransmissions of previously transmitted data increases the effective user data rate reduces, for a constant channel data rate.
Increasing transmission power can often reduce transmission errors. Consequently, increasing transmission power can reduce the relative amount of retransmissions. Correspondingly, transmission power can be reduced if the relative amount of transmission errors is sufficiently small.
U.S. Pat. No. 5,461,639 describes forward link power control in a CDMA system where error statistics are collected. The error rate is compared to a threshold. If the error rate exceeds the threshold, transmission power is increased. A code selector determines at which redundancy level to transmit. For each level of redundancy, the selector maintains a predetermined target error rate.
International Patent Application WO0013362 describes a method and device for adapting a transmission data rate or a transmitter power to the transmission quality of a transmission channel.
A channel data rate that gives an acceptable error rate at a given signal to noise ratio is selected. Transmission power is controlled.
It is also known to use medium access control and radio link control layers of a UMTS protocol structure in acknowledged mode for dedicated channels and to broadcast system information.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Physical Layer Procedures, 3G TS 25.331 v3.5.0, France, December 2000, specifies an RRC protocol. Section 8.1.1 describes broadcast of system information.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Physical Layer Procedures, 3G TS 25.322 v3.5.0, France, December 2000, specifies the RLC protocol. The RLC layer provides acknowledged data transfer service.
3rd Generation Partnership Project (3GPP): Technical Specification Group Radio Access Network, Physical Layer Procedures, 3G TS 25.301 v3.6.0, France, September 2000, specifies in chapter 5 Radio Interface Protocol Architecture of a UMTS system.
None of the cited documents describes a method and system of link control where error targets are selected as a function of transmission load in an ARQ scheme of a radio communications system.